Analog computer variable interval dispatcher for an elevator system with trip time as a measure of traffic



Jan. 21

W. H. BRUNS ANALOG COMPUTER VARIABLE INTERVAL DISPATOHER FOR AN SYSTEM WITH TR1 ELEVATOR P TIME AS A MEASURE OF vTRAFFIC BY ATTORNEY 3 m F F A R T F O E R U s A E M Jan. 21, 1969 w H, BRUNS ANALOG COMPUTER VARIABLE INTEEVAL DIsPATcHER FOR AN ELEvAToR sYsTEM WITH TRIP TIME As A Filed April 25, 1954 Sheet URZO U Al

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UZI UZZ SIU SAW TOOTH WAVE G ENE RATOR UHC CCG SCTZO SCT3G .f m U R D l m IR, T 3 D C 9 R im... D 7Nv R D .2 Z D W. G 2 n M R 2 l O D D A D l- O J D m n. i, /U D C ew w C/ w F 1 m La I O m I E. Em C S YIIIL G W N m C m M E D C/ D G DHC FIG. 4

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WILLIAM HENRY BRUNS INVENTOR EY d/wd ATTORNEY Jan. 21, 1969 w. H. BRuNs 3,422,928

ANALOG COMPUTER VARIABLE INTERVAL DISPATCHER FOR AN ELEVATOR SYSTEM WITH TRIP TIME AS A MEASURE OF TRAFFIC Filed April 23. 1964 WILLIAM HENRY BRUNS INVENTOR DY ATTORNEY I I I I I I Jan. 2l, 1969 W.,H. BRUNS ANALOG COMPUTER VARIABLE INTERVAL DISPATCHER FOR AN ELEVATOH SYSTEM WITH TRIP TIME AS A MEASURE OF TRAFFIC UMULATED TIME S ARE RUNNING UP DURING UP INTER" VAL ELAPSING4 UP RUNNING TIME ADJUSTMENT SUBTRACTS FROM SEPARATION TIME SIGNAL IF R0/2+SU ACCUMULATED TIME.

CIRCUITS Ro/Z-ONE HALF NON" STOP ROUND TRIP RUNNING TIME.

TIME ELAPSED FROM MOST RE- CENT UP DIS- PATCH.

RESETTABLE TIMER SUaTRACTs PROM SEPARATION TIME SIGNAL IF R/2+sD ACCUMULATED TIME.

Filed April 23, 1964 Sheet 4I `of 4 PROBABLE TIME wHICH wILL ELAESE WHILE MAKING A NUMBER oI-','UP AND CAR CALLS CAR CALLS w WSIPRURIIMDRRWII. REIT: N RESPECTIVELY.

DowN STOP TIME CLLTIIME CALCULATOR F' 5 h FIG4 Y- UP HALL DowN HALL cALLs CALLS su `su NOOP SD so T, CARS Ro ALLOTTED NON-STOP TERMINAL ROUND TRIP DELAY TIME TIME SEPARATION TI CALCULATOR DOWN RUNNING TIME ADJUSTMENT -lB'ACCUMULATED TIME CARS ARE AT LOWER TERM- INAL DURING UP INTERVAL ELAPSING.

UPPER TERMINAL DISPATCHING MECH' AN|SM- PoR LOWER +IT-ACCUMULATED TIME CARS ARE AT UPPER TERM- TERMINAL INAL DURING UP INTER- VAL ELAPSING. ExPIRATION OF UP DISPATCH AMOUNT OF TIME INTERvAL. INCLUDED IN UP DISPATCH INTERvAL. I I LOWER TERMINAL COMPARISON D|5p ADJUSTMENT CIRCUIT CIRCUITS SUBTRACTS FROM SEPARATION TIME SIGNAL IF M E CH.

UP DISPATCH SIGNAL CIRCUITS RCI/ZONE HALF NON STOP ROUND TRIP RUNNING TIME.

LOWER TERMINAL DISPATCHING MECHANISM.

FIG. 6

*ITACCUMULATED TIME CARS ARE' AT UPPER TERM' INAL DURING DOWN INTER VAL ELAPSING.

. I I I I I I I I I I I I I IB-ACcUMUL ATED TIME l CARS ARE AT LOWER TERM' INAL DURING DowN INTER- ExPIRATIoN OP DOWN DISPATCH vAL ELAPsING` I INTERVAL RESETTABLE TIMER I "PAIRE PROM MOST I RECENT DOwN AMOUNT OP TIME IN- DISPATCH- CLUDED -IN DowN DIs- I PATCH INTERVAL. I I

DISP. UPPER TERMINAL MECH C'rgll'o" ADJUSTMENT CIRCUITS I IJwN DISPATCH SIGNAL FIG. 5 AND DISPATCHING MECHANISMS SUBTRACTS FROM SEPARATION TIME SIGNAL IF IWILLIAM HENRY BRUNS INVENTOR l BY ATTORNEY United States Patent O 19 Claims ABSTRACT OF THE DISCLOSURE A dispatching and control system for selectively starting :a group of elevator cars from both an upper and a lower terminal in response to dispatching signals generated at timed intervals. The amount of time included in each interval is derived independently for each terminal from a calculated separation time. The separation time is calculated by computing a probable round trip time for a car as a function of an estimated number of stops which the calls then in registration indicate the car will make in traveling from one terminal to the other and back. The separation time is equal to the probable round trip time divided by the number of cars operating under the control of the system. Individual dispatching intervals for either terminal differ from this separation time in accordance with the amount lby which previous dispatching intervals deviate from it. The amount of the deviations alter successive dispatching intervals until they equal the separation time. A dispatching signal for either terminal is generated upon a predetermined relationship existing between the magnitude of a signal characteristic of the time elapsed from the start of a dispatching interval for that terminal and the magnitude of a signal characteristic of the time included in that dispatching interval.

This invention relates to a dispatching and control system for a group of elevators.

Previously, elevator dispatching and control systems have been designed to control the performance of the elevators according to predetermined operating modes. Each of these modes or operating conditions was designed to suit a specific type of traffic demand, and the system would switch from one operating condition lto `another in response to changes in the existing trai-hc demand. There are circumstances, however, in which :such systems have been found too inflexible to provide at all times optimum elevator service. This invention is directed to a more flexible method for dispatching and controlling the movements of the several cars of an elevator system.

It is accordingly an object of this invention to provide an elevator dispatching Iand control system which reflects each change of traffic or -operating condition of the elevators in the control it exerts over the movements of the cars.

One of the features of the invention is that cars are dispatched from both an upper tenminal and a lower terminal at independently generated Adispatching intervals.

Another feature of the invention is that each car is dispatched at the end of an interval calculated in accordance with the number of registered calls in the system during that interval, the time spent by cars moving during that interval and the spent by cars located at the terminals during that interval.

Yet another feature is that the control system is constantly evaluating the level of work that is to be performed by the cars at each instant and the ability of the cars that are then in service to perform this work. This evaluation is used to compute the instants in time when cars are to be started from terminal ydispatching stations to assist Mice in performing this work. In so doing, it is recognized that the .oar being dispatched at any given instant will in all probability encounter somewhat different actual work requirements during its active period.

In the structure of 'a preferred control system in accordance with the invention various signals representative of discrete system data are used by computer-s in calculating and generating intervals at which it is desirable to dispatch cars for travel toward the distant terminal. At the expiration of each calculated interval the computer transmits a signal indicative of this fact to its associated dispatcher causing the dispatcher to transmit a dispatching signal to the controllers of the cars in the group. Upon being received -by the controller of the car selected as the next one to leave the associated terminal the dispatching signal causes the selected car to start toward the distant terminal.

In the presently preferred arrangement the selection of arrangement a car may be selected for dispatch under two arrangment a car may be selected for ydispatch under two conditions. First. when it is in service and standing at the appropriate terminal. Second, when it is unoccupied, is moving beyond the farthest hall call for its direction of movement and there is no car available for dispatch from the appropriate terminal when the terminal dispatcher transmits a dispatching signal.

The invention also makes possible means for reversing the lowest down travelling empty car if it is below the lowest down hall call and dispatching it toward the upper terminal in place of a selected car standing at the lower terminal; provided no car call has been registered in the selected car, and also provided that no up traveling car ifs between the lowest down traveling car and the lower terminal. The reversal takes place upon the expiration of the dispatching interval for the previously selected car.

An understanding of the manner in which the invention is carried out in the presently preferred arrangement, and Various features and advantages thereof will be gained from the following description and appended claims when considered in conjunction with the accompanying drawing.

In the drawing:

FIGURES l and 2 taken together are 4a simplified diagram of dispatching and selection circuits employed in the system;

FIGURE 3 is a simplified schematic diagram of an up stop time calculator employed in the system;

FIGURE 4 is a `simplified schematic diagram of a down stop time calculator employed in the system;

FIGURE 5 is a simplified schematic diagram of up and down dispatching interval computers employed iny the system.

FIGURE 6 is la block diagram of the interconnection between the equipment of FIGURES 3, 4 and 5 and the dispatching mechanism of the system.

The electromagnetic switches in the system are designated as follows:

AR-Auxiliary Reversal Relay AS-Substitution Relay CCO- Car Operating Switch CCU-Up Car Call Relay CD-Car Down Switch CU-Car Up Switch DG-Direotion Determining Relay DS-Down Stop Switch DSR-Down Signal Relay EC-Empty Car Switch GAS-Group Substitution Relay GDS-Group Down Signal Relay GSCB-Group Lower Terminal Selected Car Switch GUS-Group Up Signal Relay HG-Car Call Above Relay 3 HI-Hall Call Above Relay IB-Lower Terminal Car Switch IT-Upper Terminal Car Switch LC-Lo-west Car Relay LH--Hall Call Below Relay ML-Lower Termin-al Relay RU-Up Reversal Relay SCB-Lower Terminal Selected Car Switch SCT-Upper Terminal Selected Car Switch TL-Upper Terminal Relay US-Up Stop Switch USR-Up Signal Relay Throughout the description which follows, these letters will be applied to the coils of these switches. Also, with reference numerals appended thereto, they will be applied to their contacts. In general, only the circuits for one elevator have been shown. However, where it is desirable that lthe effect imparted by the additional cars in the group be considered, the circuit components of that elevator bear the subscript a in their -desigations and the relevant portions of an additional circuit are shown in dotted line as representative of the other elevators in the group. In the description portion which follows Ilower case subscripts a and b have been used to differentiate between like components of different elevators.

It is believed the invention may be more readily understood if a brief general description of the structure precedes a more detailed explanation of the invention.

The upper and lower terminal dispatchers are carused to transmit dispatching signals to the controllers of the cars in the group by signals indicative of the expiration of desired intervals ybetween dispatched cars. These interval signals are generated by the down and up dispatching interval computers for transmission to the dispatchers at the end of each interval as calculated by the computers. The calculations are made in accordance with certain operating constants and certain operating variables of the system. Included in these variables are the number, the distribution and direction of travel of the in-service cars of the group as well ras the up direction and down direction trafiic demands in registration. A car is ,regarded as being in group service when its respective car operating switch CCO is in the operated condition; which condition exists when its emergency stop switch 'contact EMS (FIG. 2) and its load weighing switch contact LS1 (FIG. 2), operable when the car is substantially fully loaded, are both in the unoperated condition.

The trafic `demand at any instant for a given direction is calculated as the time to be lspent in making the probable average number of stops to be made in that direction of travel as a result of the number of registered hall calls for that direction at floors intermediate the terminals and the number of car calls registered in those cars selected for or actually traveling in the given direction. The cars in question are identified by having their selected car switch (SCB or SCT-FIG. 2) or their car direction switch (CU or CD) energized. Cars which have reached the distant terminal are not included in the calculation of stop `time for travel toward that terminal. Separate signals representing the probable times to be spent in making the average number of stops for each direction are delivered to the up and ydown dispatching interval computers from a pair of stop time calculators, one for each direction.

The distribution of the in-service cars in the group, another of the enumerated operating variables of the system used in calculating the desired intervals, is determined from the in-service cars standing at the terminals. These include selected cars as well as nonselected cars which have not been dispatched. A car is indicated to be an in-service car that is standing at the terminal when its respective terminal car switch (IB or IT-FIG. 2) is in its energized condition- Such a car may be either selected to be next dispatched or awaiting such selection.

The operating constants of the system which are utilized in calculating the desired intervals between dispatched cars include the nonstop round trip traveling time of a car of the group without terminal delays and the allotted idling time at both terminals. In addition, of course, the average time delay for a stop at an intermediate landing is used in calculating the traf-lic demand, as has been explained earlier. Circuit components or voltage inputs which are representative of these constants are incorporated in the system but absolute values therefor are not Shown, as this is a matter for design choice.

Referring to the drawing, FIGURE 1 depicts various coil excitation circuits including a circuit containing lowes-t car relays LCa, etc., used to detect the lowest car in the group. The operation of that circuit depends upon the operating characteristics of the operational amplifiers OAlSa, etc., and the forward drop of the blocking rectifiers in the lowest car contact circuit on the selector. As is customary with operational amplifiers the input resistor and the individual amplifier feedback lresistors 102, etc. are coordinated in size to give amplifiers OA15a, etc., the desired gain. Also, as is customary, when one of amplifiers OAlSa, etc., is conducting the voltage at its input is near zero potential with respect to ground. Thus, conduction by the amplifier corresponding to the lowest car in the group causes the voltage at the lowest car contact point in contact with brush LCB associated with the lowest car to be at a potential above ground which is substantially equal to the potential drop across its associated rectifier D8. As a result, the potential of all higher iioor bar contacts associated with the floors at which other cars are located is less than this value and the other amplifiers corresponding to those cars above the lowest car cannot conduct. This results beca-use the circuit from the lowest car floor bar contact to the input circuits of such other amplifiers includes at least two rectifiers in vseries connection whose forward drop causes the input signals to such other amplifiers to be insufficient to cause them to conduct. Since only the amplifier corresponding to the lowest car in the group conducts, -only its lowest car relay is actuated. As was earlier explained, the car operating switch CCO (FIG. 2) is energized only when i-ts associated car is in group service. Its contacts CCO4 in series with amplifier OA'15 prevents a car which is not operating under control of the system from being selected as a lowest car. Contacts IBS of the lower terminal car switch, in circuit with the lower terminal floor bar contacts MLCC prevent the operation of the lowest car relay of a car located at the lo-wer terminal until that car has been dispatched for travel in the up direction. This permits the selection of a car approaching the lower terminal until a dispatching operation occurs after which its selection as low car is prevented. The selector advancer panel brushes LCB are of sufficient length to bridge contacts at adjacent floors, thus maintaining a lowest car relay energized when the car is between landings.

In FIGURE 2 additional coil excitation circuits are shown including those containing the coils of upper terminal relay TL, lower terminal lrelay ML, upper terminal selected car switch SCT and lower terminal selected car switch SCB. Selector advancer panel brush MLB coacts with iioor lbar contacts TLC and MLC to complete the circuits for the coils of relays TL and ML when the advanced position of the car with which they are associated is at the upper and lower terminal landings, respectively. The circuit for the coil of 'switch SCB includes the brush SSBB and one contact SSBC of a stepping switch associated with the lower terminal. This stepping switch operates to scan the cars of the group in rotational non'sequential order by stepping from contact to contact, each of its contacts being associated with a different car in the group, until it completes a circuit for the coil of a switch SCB associated with one of the cars. When that occurs the switch operates, selecting the associated car as the next to be dispatched to travel up. `It also opens a pair of its contacts (not shown) to stop the stepping switch operation in any well known manner. The circuit for the coil of switch SCT contains the brush SSTB and one contact SSTC of a stepping switch associated with the upper terminal. The operation of this stepping switch is comparable to that of the stepping switch used in selecting cars at the lower terminal.

Shown in FIGURE 3 is circuitry comprising various interconnected operational amplifiers with associated cooperating components used in the up ystop time calculator. The operational amplifiers used are commercially purchasable and all amplifiers are identical.

Each input circuit to operational amplifier UOA1 is connected through a resistor URI and parallel contacts SCB2 and CU1 -to an output circuit CC from the car call registering means of one car in the group. In the presently preferred arrangement wherein each car ca'll registering means uses an electron-emitting gas filled tube having a load resistor in its cathode circuit, the output circuit CC of each car is connected to the cathode end of the load resistor of all the tubes in that car. in the course of operation an in-put to amplifier UOA1 is completed through resistor R1 and contacts SCBZ or CUI for each car designated for up travel and not located a-t the upper terminal (hereinafter such cars are referred to as up cars). The input signals to UOA1 are positive polarity voltages with respect to ground and represent the number of registered car calls in all up cars. A feedback for each car in the group is connected around amplifier UOA1. During operation the feedback path for each up car is completed through resistor URZ and contacts SCB3 or CU2. Such feedback circuits cause the output signals of UOA1 to represent an average of the number of registered car calls in all up cars. Output signals from UOA1 have a negative polarity with respect to ground potential. Resistors UR1 and URZ are coordinated in values so as to cause amplifier UOA1 to produce an output signal variable from zero volts to a maximum value which is just below the amplifier saturation voltage when the number of existing registered car calls is varied from zero to the maximum number which can exist in one car in the `specific installation. The maximum voltage value below the saturation voltage chosen for the Philbrick P65A amplifiers used for all amplifiers in the embodiment herein described is approximately l0 volts. Amplifier UOA1 is scaled in accordance with the maxim-um number of car calls that can exist in a certain installation so that each volt of the output signals of UOA1 represents a certain number of calls. Resistor URS and condenser UCS in the output circuit of amplifier UOA1 serve to smooth transients in the output signa-ls of UOA1.

Operational amplifier UOA2 serves to produce an output signal representing the number of up hall calls in registration at intermediate landings (hereinafter referred to as yup hall cal-ls) in the installation at any instant. The input circuit to UOA2 at point UHC is connected to a circuit common to al-l intermediate landing up hall call registering means which imay suitably be of the type described above for car call registering means. The input signal to amplifier UOA2 is a variable positive polarity voltage with respect to ground Ipotential which results in a negative polarity output signal from the amplifier as a result of the 180 phase shift produced by the amplifier. Resistors URS and UR6 are chosen so as to `cause amplifier UOA2 to produce an output signal variable from zero volts to a maximum within the desirable 10 volt ran-ge when the number of existing registered up hall calls is varied from zero to the maximum number which can exist in the installation. The scale of calls per volt for amplifier UOA2 is the same as that for UOA1. Resistor UR4 and condenser UC4 smooth transients in the output signal of amplifier UOA2.

Saw tooth wave generator 31U transmits a positive polarity saw tooth wave signal which may suitably be of a voltage range from 0 to 10 volts and a frequency of about 150-200 c.p.s. to one input circuit of operational amplifier UOA3. The other input `circuit of UOA3 receives the negative polarity output signals transmitted from amplifier UOA1. The effective input signals to amplifier UOA3 are the algebraic sums of these two inputs. Amplifier UOA3 is arranged as a nonamplifying inverter the output signals of which are saw tooth shaped waves having a potential variation of ten vo-lts which `may assume any position between plus 10 and minus 10 volts with respect to ground potential according to the magnitudes of the output signals transmitted from amplifier UOA1.

The output of amplifier UOA3 is connected to the input of operational amplifier UOA4 which has two Zener diodes UZ1 and UZ2 in its feedback circuit s0 as to operate on the variable output signals from UOA3 in such manner that square wave signals are generated at its output. The maximum and minimum voltages of these square wave signals depend upon the reverse breakdown voltages of diodes UZ1 and UZ2. Diode UZ1 may suitably have a reverse breakdown potential of 2.4 volts and diode UZ2 a reverse breakdown potential of 9.1 volts to produce output potentials of square wave generator UOA4 ranging in magnitude from plus 2.4 to minus 9.1 volts. When a saw tooth wave input signal is rst applied to the input of amplifier UOA4 its feedback loop is open circuited by the diodes and its output voltage immediately assumes a potential of plus 2.4 volts, in the case of a negative input, or minus 9.1 volts in the case of a positive input. This results because the respective diode starts conduction at these potentials and clamps or stabilizes the voltage output at one or the other value. The output voltage continues at its clamped or stabilized value, notwithstanding the change in input signal during its flyback interval. If, however, the input signal changes its polarity with respect to zero or ground potential during its sweep, the output of the amplifier for successive cycles of input signal assumes the shape of a square wave having a maximum value of plus 2.4 volts and a minimum value of minus 9.1 volts. The proportioning of the square wave between positive and negative lobes will depend upon the relative proportioning of the saw tooth input between positive and negative values. This, of course, is caused by the diodes UZ1 and UZ2 responding to the output variations to control the direction of conduction in the feedback loop such that the output potential alternatively assumes its clamped or stabilized values.

The output signals of amplifier UOA4 modulate the up hall call signals from amplifier UOA2 at the input of amplifier UOAS. This modulation is performed by an onoff switching action achieved through the coaction between the square wave output signals of amplifier UOA4 and the blocking action of rectifiers UD1 and UDZ. All negative portions of the square wave output signals from UOA4 are blocked by rectifier UD1 and cannot pass to junction point U11. Thus during the times when this blocking action occurs, the entire negative output signals of UOA2 pass through resistor UR7 and rectifier UDZ to the input of amplifier UOAS. The positive portions of the square wave output signals from UOA4, however, pass through rectifier UD1 to junction point UJI at which point they have sufficient magnitude to supress entirely the negative output signals from UOA2 passing through reistor UR7 to junction point U11. Rectifier UDZ prevents any positive output signal from UOA4 reaching the input circuit of amplifier UOAS.

This results in the application to the input of amplifier UOAS of negative polarity square wave signals having a frequency equal to that of the saw tooth waves from generator 31, having magnitudes that are proportional to the number of existing up hall calls, and having durations determined by the magnitudes of the average number of existing car calls in up cars. Thus, the voltage level of resistor UR7 to junction point U11. Rectifier UDZ prethe square wave input signal to amplifier UOAS averaged over one cycle of generator 31 may be said to represent the product of the number of up hall calls existing during that `cycle multiplied by the average number of car calls per carin up cars during that cycle.

Amplifier UOAS produces positive polarity square wave output signals which are averaged in condenser UC10. Referred to the calls per volt scale of amplifiers UOA1 and UOA2 such average voltage levels represent the probable number of existing up hall calls which require stops to be made at landings at which existing car calls in fup cars also require stops to be made. Such calls are referred to as the probable number of coincident calls and are calculable because they are equal to the number of up hall calls multiplied by the average number of car calls per car in up cars divided by the number of landings intermediate the two terminals. Since the input signals to amplifier UOAS represent the number of up hall calls multiplied by the average number of car calls per car in up cars, the output signals of amplifier UOAS represent the probable number of coincident calls so long as the gain of amplifier UOAS is such as to cause its input signals to be multiplied by the reciprocal of the number of intermediate landings. Resistors URS and UR9 are so proportioned that the gain of amplifier UOAS is appropriate for its building. As a practical matter values for resistors URS and UR9 may be chosen as follows. Adjust the output signal of amplifier UOA1 to a value representative (according to the volts per call scale that has been chosen of a certain average number of car calls in up cars. Similiarly, adjust the output signal of amplifier UOA2 to a value representative of a certain number of up hall calls. The magnitudes of resistors URS and UR9 are then adjusted until the average level of output signal from amplifier UOAS, as measured across UC10, -is equal to a voltage which according to the chosen scale is equal to the calculated probable number of coincident calls. After resistor URS and UR9 are adjusted in this manner, the linear operating characteristic of amplifier UOAS below its saturation value assures the production of output signals representative of the probable number of coincident calls for any combination of up hall calls and car calls in up cars.

The negative polarity outputs of amplifiers UOA1 and UOA2 and the positive polarity output of amplifier UOAS as smoothed Lby condensers UCS, UC4 and UC10 pass through resistors UR11, UR12 and UR13 and are algebraically summed at junction point U12. The resultant signal at U12 is of negative polarity and at any given time represents the probable number of calls in registration to which the car to be dispatched at the lower terminal can respond during its up trip; and which number of calls it is anticipated will remain in registration throughout Vthat up trip. This signal passes to amplifier UOA 6 which acts to invert and multiply it in accordance with the values of resistors UR11, UR12, UR13 and UR14. The values of these Iresistors are so coordinated as to cause amplifier UOA6 to have an amplification factor that is equal in magnitude to twice the time in seconds required for an average stop at a landing. The magnitude of the positive polarity output signal from amplifier UOA6 thus is proportional according to a chosen volts per second scale to the probable time the car awaiting dispatch at the lower terminal will spend making the probable number of stops which are to be made in traveling up.

Amplifier UOA7 inverts the output signal of amplifier UOA6 for computations in which it will hereinafter be used.

FIGURE 4 shows circuitry for the down call stop time calculator. In its structure and operation it is the counterpart of the up -call stop time calculator of FIGURE 3. Accordingly, its volts per call and volts per stop seconds scales correspond in magnitude to those used in the circuit of FIG. 3.

FIGURE shows to components of the interval computers. The inputs to amplifier OAS include a circuit -SU from amplifier UOA7 (FIG. 3), a circuit- SD from amplifier DOA7 (FIG. 4), a circuit R0 which carries a signal representing the time in seconds required for a car operating at its rated speed to make a round trip without stop and circuit Tt which carries a signal representing the total time in seconds that cars may be allotted for waiting at both terminals. For each signal the same volts per second scale is employed for determining its magnitude. The sum of these signals represents the total calculated work time one car would require to complete one round trip making the probable number of stops which the up and down stop time calculators of FIGURES 3 and 4 have calculated to be required to serve the number of then existing calls. A feedback circuit around amplifier OAS through a resistor R19 and contacts CCOS is completed for each in-service car (as previously defined) in the group. The feedback circuits divide the sum of the magnitudes of the signals applied to amplifier OAS by the number of in-service cars and cause the positive polarity output signal of amplifier OAS to represent, according to a chosen volts per second scale, the theoretical time by which the in-service cars should be separated for the calculated round trip time. Resistor R20 and condenser C20 smooth the output signals and amplifier OAS before they are transmitted through blocking rectifier D4 to junction J3 which has a constant positive potential bias which is supplied through resistor R21 and rectifier D3.

The output signal from amplifier OAS is continuous and represents an average car work time, i.e., the theoretical time by which the in-service cars should be separated for the existing work load to be performed in the calculated round trip time. Thus, it also represents the theoretical dispatching interval between the cars dispatched from the lower and upper terminal. This interval is referred to as theoretical because it is an interval by which the in-service cars should be separated according to the number of calls for the up and the down directions of travel that exist at the time the signal representing such interval is being transmitted from amplifier OAS. But, in a practical elevator system some of the in-service cars would have been dispatched previously to suit time requirements for a different number of calls. These may not be separated by the presently calculated theoretical interval or separation time because their dispatching intervals deviated therefrom. Accordingly, two interval adjusting means for each terminal are provided for compensating for the result to be expected because these previously dispatched cars were not separated by the interval indicated as proper for the presently existing conditions.

The adjusting means for the lower terminal are illustrated by the circuits containing operational amplifiers UOA9, UOA10 and UOA11, UOA12. The corresponding interval adjusting means for the upper terminal include the circuitry containing operational amplifiers DOA9, DOA10 and DOA11, DOA12.

Amplifier UOA9 has an input circuit for each elevator in the active or in-service group, which circuit is completed from a positive polarity constant potential source through contacts CU3 of its car up switch which indicates it is actually traveling in the up direction. Amplifier UOA9 has condenser UC1 in its feedback loop to cause it to perform as an integrator. It also has contacts USRZ and GASl in other feedback circuit branches which engage to short circuit condenser UC1 to reset the amplifierintegrator as a car is dispatched from the lower terminal or as a down traveling car is reversed and substituted for the selected car at the lower terminal. The values of resistors UR22 and capacitor UC1 are so chosen that the output signal of amplifier UOA9 represents the actual accumulated operating or serv-ice time spent by all cars traveling in the up direction during any up dispatching interval measured between successive closings of contacts USR2 or GASl.

The negative going output signal of amplifier UOA9 is algebraically summed at junction point U14 with two positive potential signals, which in combination represent the apportioned amount of the separation time that it is calculated that the car awaiting dispatch at the lower terminal will require to complete its up trip in accordance with the probable number of stops the car will make. These positive potentials over circuits `-l-SU and +RW are, respectively, the output signal of amplifier UOA6 (FIG. 3),representing the probable amount of time the car awaiting dispatch at the lower terminal will spend making the probable number of up stops; and a positive polarity constant potential signal which, according to the chosen volts per second scale for signal R represents the time required or a car of the group to run from the lower terminal to the upper terminal without a stop between.

This combined signal at point U14 is the up running time correction signal and is supplied to the input of amplifier UOA for the purpose of producing a signal having the effect of shortening the succeeding dispatching interval. For this purpose rheostat UREl in its feedback loop and resistors 50, 51 and 52 in its input circuits are coordinated in value and so chosen of magnitudes as to control the signal amplification by the amplifier at some low value less than unity. In general, the relationship of these resistors will reflect the number of cars in the group. If desired the relationship can be made variable with changes in the number of in-service cars in a group and also variable with time. For example, the relationship can be such that the output signal from the amplifier is progressively increased as the dispatching interval being calculated increases. The exact value to be used will be determined in part at least, by the speed with which the correction is desired to be accomplished. Rectifier UDS in the output circuit or amplifier UOA10 prevents any positive signals from that amplifier affecting the theoretical interval. Thus, it is only when the input signal to amplifier UOA10 is positive that the signal can cause an adjustment to be made; and this is in the direction or sense to decrease the up dispatching interval. It causes such a decrease when from the accumulated up running time of previous dispatched cars it is anticipated that the time required to run the car in the up direction and make all probable up stops exceeds the time which the system would apportion the car for running up in accordance with the calculated separation time.

In the terminal idling time correction circuits the other interval adjusting means for the up direction, operational amplifier UOA11 has two input circuits for each elevator in the group. As indicated each of these supplies a positive or negative polarity signal through contacts IT3 or IBS during the time its associated car is standing at the top or bottom terminal, respectively. The combined input signals to amplifier UOA11 represent the instantaneous scaled numerical difference between the number of inservice cars at the upper terminal and the number of such cars at the lower terminal. Condenser UCZ in the feedback circuit around UOA11 causes the amplifier to operate as an integrator. Contacts USR3 and GASZ in parallel with the condenser engage to short circuit the condenser and reset the integrator when a selecte-d car is dispatched for up tnavel or when a down traveling car is reversed and substituted for the selected car at the lower terminal. The output signal of amplifier UOA11 represents the difference between the overall time in-service cars have spent at the upper terminal and the time they have spent at `the lower terminal during the dispatching interval being calculated, as indicated by the interval between successive closings of contacts USR3 and GASZ. Resistors UR24 and capacitor UCZ are scaled to cause the integrator to produce a voltage output which represents the actual time difference in accordance with a chosen volts per second scale.

'Ihe output signal of amplifier UOA11 is algebraically summed at junction point U with the signal along line +SD from the output of amplifier DOA6 (FIG. 4) and the signal along line -SU from the output of amplifier UOA7 (FIG. 3). The resulting signal is applied to the input of amplifier UOA12 which, like amplifier UOA10,

has its feedback loop values scaled to give it a signal amplification of less than unity. The relationship between feedback rheostat UREZ and resistors 55, 56 and 57, however, should be such as to cause the dispatching interva-ls at the lower terminal to approach zero time as the unbalance between the up and down service demands approaches down peak conditions. The negative portion of the signal from amplifier UOA12 is combined at summing point U16 to effect a further correction to the up dispatching interval time signal at that point.

The circuits containing amplifiers UOA11 and UOA12 operate to cause a potential to be subtracteed from the signal at J3 representing the theoretical interval under three conditions. First, if the time calculated to be expended for stops due to registered calls for down travel -l-SD) exceeds that calculated to be expended for stops due to registered calls for up travel SU) and/or the time spent by cars located at the lower terminal exceeds that of cars at the upper terminal; land, second, when the down travel time (+SD) exceeds the up travel time (-SU) to a degree greater than the time spent by cars located at the upper terminal (+IT) exceeds that spent by cars located at the lower termina-l (*IB); and third, if the time spent by cars located at the lower terminal (-IB) exceeds the time spent by cars located at the upper terminal (+IT) to a degree greater than the time calculated to be expended for stops due to registered calls for up travel SU) exceeds the time calculated to be expended for stops due to registered calls for down travel (+SD). These corrections act ultimately with other factors to balance the number of cars serving in each direction with the amount of service demands in that direction to maintain the cars equally separated one from the other in time.

At junction point U16 the positive potential signal from junction point 13 and negative potential :signals from amplifiers UOA10 and UOA12 are algebraically summed to obtain at all times a continuous signal representing the interval at which cars are to be dispatched from the lower terminal.

Amplifier UOA13 is employed as an integrator with condenser UC4 connected between its input and output circuits and operates as a resettable timer to generate negative potential signals representing time in seconds. The time constant of the amplifier, as determined by resistor URZS and condenser UC4, is such as to produce voltage signals at its output whose magnitudes are scaled for the same volts per second :scale as that employed for amplifier OAS. Contacts USR4 and GAS3 act as interval start switches and are used to recycle the integrator at the start of each interval when a car selected for travel in the up direction is dispatched or when a down traveling empty car is reversed and :substituted for a selected car at the lower terminal.

The negative polarity signals generated by amplifierintegrator UOA13 and signals representing the calculated dispatching intervals are combined iat junction point U17 to determine the moments at which up dispatching signals should be given. When a predetermined relationship exists between the signals appearing at junction point U17 such that a negative polarity is applied to amplifier UOA14, the amplifier operating as an inverting multiplier produces a positive signal at its output of sufficient value to energize the coil of group up signal relay GUS and operate that relay. Upon operation relay GUS causes an up dispatching signal to be given to the system as will hereinafter be explained.

The circuits including amplifiers DOA9, DOA10, DOA 11, DOA12 and DOA13 in the upper part of FIGURE 5 are the down dispatching counterparts of the up dispatching circuits which have just been explained. They are associated in the same general manner with amplifier OA8 to calcuate the times at which down dispatching signals should be given to the system in the same manner that the up dispatching circuits function for the up direction.

Amplifier DOA14 operates when the signals at junction point D17 are negative to produce a positive signal of sufficient value to cause the energization of the coil of group down signal relay GDS to operate that relay. Upon operation of relay GDS a down dispatching signal is given to the system.

An understanding of the effect of the operation of the computing apparatus of FIGURES 3, 4 and 5 on the system as a whole may be gained if it is assumed that the system has been operating under balanced traffic conditions with the demands for travel in the up direction equal to the demands for travel in the down direction and that cars are being dispatched from iboth terminals at intervals equal to the calculated theoretical interval when the demand for travel in the down direction increases. As a result the magnitude of the signal (-SD) from amplifier DOA7 (FIG. 4) is increased. This signal on connecting line -SD to the input of amplifier OAS causes its output signal to be increased in value, thereby increasing at junction point 13 the signal representing the calculated theoretical interval or the separation time. This operates ultimately to increase both the up and down dispatching intervals to compensate for the fact that the increased demand for travel in the down direction increases the round trip traveling time of the cars; which, if they are to remain equally spaced in time, must now be separated one from the other by a larger interval.

The output signal from amplifier DOA6 on line +SD is also increased to effect an increased negative signal output of amplifier DOA10. This increase at junction point D16 is of sufficient magnitude to more than offset the increase in the value of the signal from amplifier OAS. Thus the negative output signal of amplifier-integrator DOA13 causes junction point D17 to be negative in a shorter period of time than previously with the result that amplifier DOA14 produces a positive signal output to operate group down signal relay GDS in a shorter time. Relay GDS closes its contacts GDSZ in the coil circuit (FIGURE l) of down signal relay DSR, completing that circuit through contacts SCT4 of the upper terminal selected car switch SCT associated with the upper terminal selected car. Down signal relay DSR closes its contacts DSRS which short circuit the coil (FIGURE 2) of upper terminal selected car switch SCT, causing it to release and engage its contacts (not shown) which control the operating mechanism of the upper terminal scanning stepping switch to cause that switch to select another car. Also, another pair of contacts (not shown) of switch SCT engage to initiate the start of the car on its downward travel. Thus, the first car dispatched from the upper terminal after the increase in the demand for down travel is dispatched in a shorter interval than that which was being generated during the balanced traffic condition. This caused it to leave earlier to serve the increased down traffic.

The signal on output circuit -l-SD from amplifier DOA6 is also connected to the input of amplifier UOA12 to produce an increased negative signal at junction point U16, but this signal is of insufficient magnitude to offset entirely the increase in the positive potential output of amplifier OAS yappearing at U16. The negative output signal from amplifier-integrator UOA13 thereby takes a longer period of time to drive junction point U17 negative with the result that amplifier UOA14 produces a positive potential output to operate group up signal relay GUS after a lengthened interval. The operation of relay GUS causes contacts GUS2 to engage in the coil circuit (FIG- URE 1) of up signal relay USR completing that circuit through contacts SCB4 of the lower terminal selected car switch SCB associated with the lower terminal selected car and contacts RUl. Up signal relay USR closes its contacts USR6 to short circuit the coil (FIGURE 2) of lower terminal selected car switch SCB. That switch releases and engages its contacts (not shown) controlling the operating mechanism of the lower terminal scanning stepping switch to cause that switch to select another car. Also, another pair of contacts (not shown) of lower terminal selected car switch SCB engage to initiate the start of the car on its upward travel in any well known manner. Thus, the first car dispatched from the lower terminal after the increase in the demand for down travel is dispatched at a longer interval than that which preceded during the balanced traffic condition. This is done to cause the actual dispatching interval of the cars to be coordinated with the changed service demands.

At this point it will be understood that the actual intervals at which the cars are rst dispatched, as represented by voltages at summing points U16 and D16, do not equal the corresponding calculated theoretical intervals, as represented by the voltage at summing point J3. If now, for purposes of explanation, it be assumed that the service demands remain unchanged it will be seen how the actual and theoretical intervals, i.e., the dispatching interval times and the separation time, are brought into coincidence during subsequent dispatching operations.

When the top terminal interval was shortened an increased number of cars started traveling down during the next generated down dispatching interval. This causes the negative output potential of amplifier DOA9 to increase and in part offset the unbalance that was caused by the increased potential from amplifier DOA6 along line -i-SD at junction point D14 when the down demand increased. This reduction in potential Idifference during subsequent intervals causes the effective potential of D14 to become zero at the completion of some future down dispatching interval such that no signal is applied to the input of amplifier DOA10 and no corrective signal is generated.

Simultaneously, for reasons which are explained shortly, an increase takes place in the time of cars standing at the upper terminal as compared with that of cars at the lower terminal during subsequent down dispatching intervals and this causes a positive potential output from amplifier DOAII to offset the increased potential from amplifier DOA7 along line -SD at junction point D15. This is in the direction to cause the effective potential at D15 to become zero at the completion of some future down dispatching interval such that no signals are generated for transmission to amplifier DOA12.

The down dispatching interval that is generated at the time when amplifiers DOA10 and DOA12 receive no input signals is equal to the calculated theoretical interval represented by the magnitude of the output signal of amplifier OAS appearing at junction point 13.

It will be recalled that the actual up dispatch interval though initially lengthened, was not lengthened as much as the calculated one. The up moving cars now tend to reach the upper terminal before the expiration of this lengthened interval and thus stand there awaiting their down dispatch for a greater portion of the interval than heretofore. Similarly, the downwardly moving cars are held back by the increased down traffic and they spend a lesser portion of the interval at the lower terminal. This unbalances the top and bottom standing time inputs to amplifier-integrator UOA11 to produce a progressively increasing negative signal at junction U15 which initially is not as great as the increased positive signal on line -l-SD. This positive signal was initially effective to cause the actual dispatch interval though lengthened to =be shorter than the newly calculated theoretical interval. As the unbalanced standing time increases the output of amplifier UOA11 gradually increases during successive intervals until it offsets the increase in the signal on line -l-SD, with the effect that the actual up ydispatch interval ultimately equals the calculated interval.

During the time the actual up dispatching signal is being lengthened, amplifier-integrator UOA9 has been measuring the accumulated time of each up moving car during each of the intervals. Successive intervals are being lengthened and successive cars are being increasingly spaced. This may temporarily result in a change in the output of amplifier-integrator UOA9 #but this branch of the circuit is ineffective runtil the combination of the assumed unchanging signals on lines -i-SU and Rom become greater than the output of amplifier UOA9 at junction U14; whereupon this branch of the circuit functions in a manner similar to that described for its counterpart for the down direction, amplifier-integrator DOA9.

With both the upper terminal :and lower terminal dispatching intervals equal to the new calculated theoretical interval the system is once again dispatching the cars so that they are equally separated one from the other by the shortest time desirable but their dispatch from the two terminals need not be in unison.

From the foregoing, it will be understood that when the system changes from balanced operation to increased trafic in the up direction the apparatus associated with the lower terminal will function in the manner that has been described for the upper terminal equipment and vice versa.

lFurther, if the traic demand becomes greater in both directions the system operates to calculate increased dispatching intervals for both terminals and the apparatus associated with each terminal operates in the manner that has Ibeen described for that assoicated with the upper terminal.

It frequently happens that it would be desirable to reverse the direction of travel of a car approaching a terminal landing and make it available to respond to interfloor traic while retaining at the terminal the car which would otherwise have been dispatched. This can result in faster service to the registered calls and also the retention of the terminal car to care for surges of tratic originating at that position.

The manner in which the system operates to achieve the above-described results may best be understood if it is assumed that car b is at the lower terminal, selected as the car to leave at the end of the dispatching interval, but no car call is registered in it. Further, assume that car a is the lowest car, below all upwardly dispatched cars and moving toward the terminal while empty and with no landing call below it. In these circumstances the following conditions exist. Lower terminal selected car switch SCBb is in the operated condition with its contacts SCBlb and SCB7b closed. Lower terminal relay MLb is operated, its coil (FIG. 2) being energized through the circuit containing advancer panel brush MLBb and main landing floor bar contact MLCb, thereby causing contacts MLZb and ML3b to be engaged. Contacts ML2b and SCBlb complete the circuit for the coil (FIGURE 2) of lower terminal relay IBb causing its contacts IBSb to be engaged. Contacts SCB7b and ML3b complete a circuit for the coil (FIGURE 2) of group lower terminal selected car switch GSCB causing that switch to close contacts GSCBl. In the absence of a `car call in car b contacts HGlb of the car call above relay HGb (coil circuit not shown) are open in the coil circuit (FIGURE 2) of up car call relay CCU. Relay CCU is in the released position with its contacts CCUl engaged. Since the circuit to amplifier OAlSa (FIGURE 1) is the lowest completed amplifier circuit lowest car relay LCa is in the operated condition with its contacts LCla closed. Direction determining relay DGa is in the released position with its contacts DGla closed since car a is traveling down. Contacts DSZa are closed, down stop relay DSa (coil circuit not shown) being in the released position since car a is not stopped in answer to a registered call. Empty car switch ECa is operated and its contracts EC3a are closed, its coil being energized through load weighing switch contacts LS2a. Contacts LH2a of hall call below relay LHa (coil circuit not shown) are closed in the absence of a hall call below car a. Up signal relay USR is in the released position and its contacts USRl are closed since group up signal relay GUS has not operated to close its contacts GUSZ in the coil circuit (FIGURE 1) of relay USR. Up reversal relay RU and auxiliary reversal relay ARa are operated, their coil circuits (FIGURE 1) being completed through contacts GSCBl, CCUl, USRl, DGla, DSZa, EC3a, LOla and LHZa. Contacts RUI are open in the coil circuit of up signal relay USR preventing the energization of that coil when the up dispatching interval expires. Contacts ARla are closed in the coil circuit (FIG. 1) of substitution yrelay ASa to prepare a circuit for that relay being energized when contacts GUS3 close upon the expiration of the up dispatching interval.

When the up dispatching interval expires and group up signal relay GUS is operated to close its contacts GUS3, substitution relay ASa is operated, its coil circuit being completed through contacts GUS3, ARla and contacts ASZ of the other cars in the group. When relay ASa operates it closes its contacts AS4a in the coil circuit (FIGURE l) of group substitution relay GAS and its contacts ASla in the coil circuit of direction determining relay DGa. Group substitution relay GAS operates to close its contacts GASl, GAS2 and GAS3 to short circuit feedback condensers UCl, UC2 4and UC4 and recycle amplifiers UOA9, UOA11 and UOA13 (FIGURE 5) to start generation of the next up dispatching signal. Direction determining relay DGa operates to open its contacts (not shown) which cause car a to stop and reverse its direction of travel at the iirst iioor encountered by its advancer panel after the operation of relay DGa. In the meantime car b remains the selected car at the lower terminal to await a subsequent up dispatching signal which will operate relay USR to cause car b to run up.

From the foregoing description it will also be understood that the system is capable of reversing a car short of its terminal under circumstances where no car is available at the terminal for dispatch at the end of the dispatch interval. These operations are known per se, having variously been designated as late car reversal or high or low call reversals. It is not deemed necessary to describe at length the circuit operations incident to their accomplishment as this will be evident from a study of the circuit drawing.

In passing it should be noted that the source of positive potential connected at junction point J3 (FIG. 5) is scaled to produce a desired minimum dispatching interval beyond which no reduction is permitted regardless of the lack of calls.

Similarly, if it is desired to anticipate peak traic conditions that are to occur at a predictable time, clock controlled contacts may be so connected as to supply a maximum acceptable positive potential at the output of amplifier UOA6 or DOA6 depending upon the nature of the expected peak. In the described embodiment this maximum value would be in the order of l0 volts.

Furthermore, if desired the calculated stop times may be made self-adjusting to conform to the actual stop times experienced. Such a corrective means for the calculated up stop time might take the form of an adaptive loop circuit to change the value of feedback resistor UR14 or it could take the form of another input circuit to amplifier UOA6 at junction point U12. This circuit would carry a signal proportionally equal to the diterence between the average output signal of amplifier UOA9 and the signals on lines -j-SU and -j-Ro/z. Such a signal, when of a positive potential would indicate that the calculated stopping time was too great in comparison to the actual stop time and would cause such calculated time to be decreased; and when of a negative potential would indicate that the calculated stopping time was too small and would cause it to be increased. A corresponding corrective measure for the calculated down stop time could be made at amplifier DOA6.

It is not intended to set forth all the variations that may be made, but it is contemplated that many of the features of the invention disclosed may be carried out in other ways, and may be used in connection with apparatus and circuits different from those speciiically described; and that many apparently widely different embodiments of the invention can be made without departure from the spirit and scope of the invention. It is therefore intended that all matter contained in the above description or shown in the accompanying drawing shall be interpreted as illustrative and not in a limiting sense.

What is claimed is:

1. A dispatching and control system for selectively starting a plurality of elevator cars from a dispatching terminal at timed intervals in response to dispatching signals for travel toward an opposite terminal, comprising: computing apparatus including a plurality of interconnected operational amplifiers continuously operating in response to conditions indicative of the existing service demand, said apparatus calculating the time it would take a car to complete a round trip from one terminal to the other and back while making an estimated number of stops which said service demand indicates the car will make during such travel and continuously producing a rst electrical signal, the magnitude of which according to a predetermined scale 'is proportional to the amount of said calculated round trip time divided by the number of said cars; an interval start switch operating at the start of each separate dispatching interval; an integrating operational amplifier operating as a timer in response to each operation of said interval start switch and producing a second electrical signal, the magnitude of which during each interval is according to said predetermined scale proportional to the amount of time elapsed from the operation of said interval start switch for that interval; and a dispatching signal switch operating in response to the magnitudes of said first and second electrical signals and generating a dispatching signal whenever a predetermined state exists between said magnitudes.

2. A dispatching and control system according to claim 1, including: means operating to indicate a car is empty; means associated with said dispatching landing for selecting cars for dispatch from said landing; dispatching means operative to dispatch a selected car from said dispatching landing upon the generation of a dispatching signal; and means actuated in response to the travel of a car, indicated to be empty by the operation of said empty car indicating means, toward said dispatching landing for preventing the operation of said dispatching means.

3. A dispatching and control means according t0 claim 2, including: means controlling the direction of travel of the cars and stopping means responsive to the actuation of said means preventing the operation of said dispatching means for causing said car indicated to be empty to stop whereupon said direction controlling means operates to change the direction of travel of said car.

4. A dispatching and control system according to claim 3, including: means responsive to the actuation of said means preventing the operation of said dispatching means for causing the generation of a new dispatching signal.

5. A dispatching and control system according to claim 4, in which said means for preventing the operation of said dispatching means can only be actuated if said car indicated to be empty is closer to said terminal landing than any other car traveling either toward or away from said landing, it is beyond all hall calls for its direction of travel and the selected car has no car call registered in it.

6. A dispatching and control system for selectively starting a plurality of elevator cars from a dispatching terminal in response to dispatching signals for travel toward an opposite terminal, comprising: computing apparatus including a 4plurality of interconnected operational amplifiers continuously operating in response to conditions indicative of the existing service demand, said apparatus calculating the time it would take one car to complete a round trip from one terminal to the other and back while making an estimated number of stops which said service demand indicates the car will make during such travel and continuously producing a first electrical signal, the magnitude which according to a predetermined scale is proportional to the magnitude of said calculated round trip time divided by the number of said cars; an integrating operational amplier operating as a timer in response to each separate dispatch of a car from said dispatching terminal and producing a second electrical signal, the magnitude of which according to said predetermined scale is proportional to the amount of time elapsed from the most recent of said dispatches; and a dispatching signal switch operating in response to the magnitudes of said first and second electrical signals and generating a dispatching signal whenever a predetermined state exists between said magnitudes.

7. A dispatching and control system for selectively starting a plurality of elevator xcars from a dispatching terminal at timed intervals in response to dispatching signals for travel toward ian opposite terminal, comprising: cornputing apparatus of the analog variety employing a plurality of interconnected operational ampliers continuously operating in response to conditions indicative of the existing service demand, said apparatus calculating the time it would take one car to complete a round trip from one terminal to the other and back while making an estimated number of stops which said apparatus calculates the c'ar will make in response to said service ldemand during such travel and continuously generating a first electrical signal, the magnitude which according to a predetermined scale is proportional to the least amount of time by which each car could be separated from its next previously dispatched car if all successively dispatched cars were separated one from the other by equal amounts of the total `calculated round trip time; an interval start switch operating at the start of each separate dispatching interval; an integrating operational amplifier operating as a timer that is resettable in response to each separate dispatch of a car from said dispatching terminal and to each operation of said interval start switch and generating a second electrical signal, the magnitude of which during each interval is according to said predetermined scale proportional to the amount of time elapsed from the operation of the interval start switch for that interval; a comparison circuit comparing the magnitude of said first signal with the magnitude of said second signal; and a dispatching mechanism operating in response to the existence of a predetermined state of comparison and when operated generated Ia dispatching signal.

8. A dispatching and control system for selectively starting a plurality of elevator cars at timed intervals from a dispatching terminal in response to dispatching signals for travel toward an opposite terminal, comprising: an interval start indicating switch operating to indicate the start of each separate dispatching interval; an integrating operational amplifier open-ating as a resettable timer and generating in response to each operation of said interval start indicating switch a voltage of increasing magnitude of one polarity, the magnitude of said voltage during each interval being proportional to the amount of time elapsed from the operation of said interval start indicating switch for the interval; a computing apparatus including a plurality of interconnected operational amplifiers continuously generating a voltage of a polarity opposite said one -polarity and of a magnitude proportional to an amount of time which, in accordance with conditions indicative of the existing service demand and determinative of the round trip operating time of a car, is computed by said apparatus to be the least amount of time by which each car could be separated from its next previously dispatched car in order for all successively dispatched cars to be separated Ione from the other by equal intervals of time; and a dispatching signal switch providing a dispatching signal whenever a predetermined relationship exists between said voltage magnitudes of opposite polarity.

9. A `dispatching and control system for selectively starting a plurality of elevator cars from a dispatching terminal in response to dispatching signals for travel toward an opposite terminal, comprising: irst computing apparatus including a circuit of interconnected operational amplifiers continuously generating a first voltage of one polarity and of a magnitude proportional to an amount of seperation time which, according to conditions indicative of the existing service demand and determinative of the round trip operating time of a car, is computed by said first apparatus to tbe the least amount of time by which each car could be separated from its next previously dispatched car in order for all successively dispatched cars to be separated one from the other yby equal intervals of time; an integrating operational amplifier operating as a timer and during each dispatching interval generating a voltage of a polarity opposite said one polarity and of increasing magnitude proportional to the amount of time elapsed from the next previous dispatch of a car from said dispatching terminal; second computing apparatus including an additional circuit of interconnected operational amplifiers continuously generating a voltage which said second computing apparatus co-mbines with siad rst voltage to produce a second voltage of said one polarity and of a magnitude proportional to the amount of time included in a ldispatching interval as computed by said second apparatus in accordance with said separation time and the deviation therefrom in the dispatching intervals of previously dispatched cars; and a dispatching signal switch operating in response to said second voltage and said voltage of increasing magnitude and thereby providing dispatching signals for said cars whenever a predetermined condition exists between the magnitudes of said voltages; whereby whenever a dispatching interval deviates from said computed separation time the circuit of interconnected operational amplifiers of said second computing apparatus operates to alter said second voltage until said dispatching signals are starting successively dispatched cars at intervals substantially equal to said computed separation time.

10. A dispatching and control system for providing dispatching signals to dispatch separately each of a plurality of elevator cars from at least one of two terminal landings at the end of dispatching intervals, comprising: car and hall call registering means for registering calls for service to a plurality of landings; in-service means operating to indicate the number of cans in service; means providing an electrical signal the magnitude of which is according to a predetermined scale proportional to the amount of time required for one car to complete a nonstop round trip from one terminal to the other an-d back; means providing lan electrical signal the magnitude of which is according to said scale proportional to an amount of time allotted a car for delay at the terminal landings; stop time calculating apparatus operating in response to the calls in registration and continuously generating an up stop time signal and a down stop time signal, the sum of the magnitudes of which is according to said scale proportional to the probable amount of time which will elapse while a car makes a number of stops calculated by said apparatus to serve the car and hall calls in registration having taken into account in the calculation the probable number of such calls which are coincident calls; computing apparatus algebraically summing the magnitudes of the stop time signals of said calculating apparatus, with the magnitudes of the nonstop round trip time signal and the terminal delay time signal, said computing apparatus also operating in response to the operation of said in-service means to divide the sum it computes by the indicated number of in-service cars and producing continuously a separation time signal the magnitude of which according to said scale is proportional to the least amount of time by which each car could Ibe separated from its next previously dispatched car in order for all successively dispatched cans to be separated one from the other by equal intervals of time; an integrating circuit separately operative throughout each dispatching interval that elapses for producing a signal the magnitude of which is according to said scale proportional to the accumulated service time during that interval of all cars traveling from terminal to terminal in a given direction; a summing circuit algebraically summing the magnitude of said accumulated service time signal with the sum of one-half the magnitude of the nonstop round trip time signal and the magnitude of the calculated stop time signal for said given direction, said sum-ming circuit producing a running time correction signal whenever the magnitude of the accumulated time signal is less than the sum of the magnitudes of the other two signals with which it is algebraically summed and operating to reduce the magnitude of the separation time signal by the magnitude of said running time correction signal; an interval start switch oper-ating at the start of each separate dispatching interval; an electronic timer operating in response to each operation of said interval start switch and producing a signal the magnitude of which during each interval is according to said scale proportional to the time elapsed from the operation of said interval start switch for that interval; a dispatching signal switch operating in response to both the reduced magnitude of said separation time signal and the magnitude of said elapsed time signal produced by said timer and time; and means responsive to said combining means for generating a dispatching signal when said combined signals assume a predetermined relationship.

11. A dispatching and control system for a plurality of elevator cars serving a plurality of landings including upper and lower terminal landings comprising: means for providing dispatching signals for dispatching a car at the termination of a dispatching interval from the upper ter-minal; and means for providing dispatching signals for dispatching a car at the termination of a dispatching interval from the lower terminal; said two means including, an operational amplilier arranged as an integrator associated with the upper terminal and an operational amplifier arranged as an integrator associated with the lower terminal, each said integrator generating a signal of a first polarity representing time elapsed from the next previous dispatch of a car from the terminal with which the integrator is associated, operational amplifiers connected as computing mechanism for generating a signal of a polarity opposite to said first polarity representing the amount of time provided in a dispatching interval in accordance with conditions affecting the operation of the cars, and mechanism combining said iirst polarity signal associated With either one of the terminals with said opposite polarity signal for providing a dispatching signal for dispatching a car from said one terminal upon said combined signals assuming a predetermined state.

12. In Ian elevator dispatching and control system as in claim 11 for selectively starting a plurality of cars serving a plurality of landings located between upper and lower terminal landings at timed dispatching intervals, in which system the magnitudes of the timed dispatching intervals are a function of the number of registered calls; up and down landing call registering means for use -by intending passengers in registering calls for travel from said landings; car call registering means for use by passengers in registering calls for travel to said landings; individual stopping means associated with each car for stopping its respective car in response to landing calls and to its own car calls; up car means indicating a car is an up car if it is selected for travel in the up direction toward said upper terminal or is actually on a trip toward said upper terminal; down car means indicating a car is a down car if it is selected for travel in the down direction toward said lower terminal or is actually on a trip toward said lower terminal; up stop means operating at any time under the control of the number of registered up landing calls land the number of car calls registered in up cars and as a function of coincidence between the number of up landings calls then registered at landings for which car calls are then registered in up cars and determining the estimated number of up stops a car will make in response to up landing calls and car calls while traveling up from the lower terminal to the upper terminal; and down stop means operating at any time under the control of the number of registered down landing calls andthe number of car calls registered in down cars and as a function of coincidence between the number of down landing calls then registered at landings for which car calls are then registered in down cars and determining the estimated number of down stops a car will Amake in response to down landing calls and car calls while traveling down from the upper terminal to the lower terminal.

13. A dispatching and control system for dispatching a plurality of elevator cars from a dispatching landing in response to 'dispatching signals, comprising: car and hall call registering means; calculating apparatus operating in response to the number of calls registered and continuously generating signals the `sum of the magnitudes of which is proportional to the number of stops a car would make, as calculated by said apparatus, to serve the number of calls registered, said apparatus being arranged to take into consideration in its calculations the probable number of such calls which are coincident calls; an inservice switch for each car operating to indicate that its respective car is in service; computing circuits including an operational amplifier which operates in response to the sum of the magnitude of the signals generated by said calculating apparatus and in response to the number of operated in-service switches, said circuits continuously generating a separation time signal the magnitude of which is proportional to the least amount of time by which each car could be separated from its next previously dispatched car in order for all successively dispatched cars to be separated one from the other by equal intervals of time; additional computing circuits including a plurality of interconnected operational amplifiers which operate in response to the deviation from said separation time in the dispatching intervals of previously dispatched cars and generating a signal which said additional computing circuits algebraically add to said generated separation time signal to produce a signal the magnitude of which is according to a predetermined scale proportional to the amount of time included in a dispatching interval; an integrating operational amplifier operating as a timer which is resettable upon the dispatch yof each car from said dispatching landing and which during each interval produces a signal the magnitude of which is according to said predetermined scale proportional to the time elapsed from the most recent of each separate dispatch; and a dispatching signal switch oeprating in response to said signal proportional to the amount of time included in a dispatching interval and said signal proportional to said elapsed time, said dispatching signal switch generating dispatching signals when the magnitude of said signals are substantially equal to each other, the interconnected operational ampliiiers of said additional computing circuits altering their generated signal until the magnitude of a dispatching interval signal is substantially equal to the magnitude of the separation time signal.

14. A dispatching and control system for a plurality of elevator cars responsive to registered calls and serving a plurality of landings including at least one terminal landing from which cars are dispatched at timed dispatching intervals, comprising: computing circuitry including a plurality of interconnected operational amplifiers operating in response to conditions indicative of the existing service demand including the calls in registration, said computing circuitry continuously generating a seperation time signal which in accordance with said conditions is proportional to an amount of separation time calculated by said computing circuitry to be the least amount by which each car could be separated from its next previously dispatched car in order for all successively dispatched cars to be separated one from the other by equal intervals of time; a summation circuit operating in response to said separation time signal and continuously providing a signal the magnitude of which at any given instant is proportional on a time scale to the amount of time to be included in a dispatching interval as determined by said separation time at `that instant, the amount of time to be included in a dispatching interval differing from said separation time at any given instant in accordance with the extent to which the dispatching intervals of previously dispatched cars deviated therefrom; and additional computing circuitry including a plurality of interconnected operational amplifiers operating in accordance with the deviation from said separation time in the dispatching intervals of previously dispatched cars and providing signals to said summation circuit which modify the dispatching interval signals until the amount of time included in a dispatching interval is substantially equal to said separation time.

15. A dispatching and control system for selectively starting a plurality of elevator cars at timed intervals from at least one of two terminal landings comprising: car and hall call registering means for registering calls for service; in-service means operating to indicate the number of cars in service; means providing an electrical signal the magnitude of which is Vaccording to a predetermined scale proportional to the amount of time which would elapse while a car made a nonstop round trip from said one terminal to the other and back; means providing an electrical signal the magnitude of which is according to said scale proportional to an amount of time allotted a car for delay at the terminal landings; stop time calculating apparatus operating in response to the registered calls and continuously generating up and down stop time signals, the sum of the magnitudes of which are according to said scale proportional to the probable amount of time which will elapse while a car makes a number of stops calculated by said apparatus to serve the car and hall calls in registration, said apparatus being arranged to take into consideration in said calculation the probable number of registered car and hall calls which are coincident calls; computing apparatus algebraically summing the magnitudes of the stop time signals of said calculating apparatus with the magnitudes of the nonstop round trip time signal, and the terminal delay time signal, said computing apparatus including an operational amplifier and also operating in response to the operation of said in-service means to divide the sum it computes by the indicated number of in-service cars and continuously producing an electrical signal the magnitude of which is according to said predetermined scale proportional to the amount of time to be included in a dispatching interval; an electronic timer operating in response to each separate dispatch of a car from said one terminal and producing a signal the magnitude of which is according to said predetermined scale proportional to the amount of time elapsed from the most recent of said dispatches; dispatching mechanism operating in response to said signal proportional to said dispatching interval time and said signal proportional to the amount of time elapsed from the dispatch of a car and producing a signal indicating the expiration of a dispatching interval whenever a predetermined relationship exists between the magnitudes of said signals; means associated with said one terminal for selecting cars for dispatch in a direction away from said terminal; and means responsive to the signal indicating the expiration of a dispatching interval for starting a selected car.

16. In a dispatching and control system for a plurality of elevators serving a plurality of landings, including terminal landings at which cars vare successively selected as next to be dispatched for travel in each of two directions at the end of timed intervals, said cars and landings each having means for registering calls for service to the various landings, calculating apparatus computing with respect to Iboth terminals said timed intervals by which successively dispatched cars are separated, said apparatus including a plurality of interconnected operational amplifiers operating continuously in response to the landing calls and car calls in registration at any given instant and calculating the probable total work time that would be required for one car operating alone to perform the amount of work indicated as being required by the calls then in registration, said apparatus continuously producing a signal the magnitude of which is proportional on a predetermined time scale to said probable total work time and apportioning that signal between the two directions of travel, in-service means operating in response to the number of cars then under control of the dispatching and control system, an operational ampliiier operating as an averaging device in response to the operation of said inservice means and to the calculated probable total work time signal and computing the average car work time for performing said work by dividing the magnitude of said total work time `signal by the number of cars under control of the system, said averaging d'evice continuously producing a signal the magnitude of which is proportional on said predetermined time scale to said average car work time, an integrating operational amplifier measuring the actual accumulated car operating time for a given ydirection of travel during each interval being computed for said given direction and producing a signal the magnitude of which is proportional thereto, a iirst summation circuit continuously comparing said accumulated time signal to the apportioned calculated probable work time signal for that same direction of travel and deriving when the magnitude of the apportioned calculated time signal exceeds the magnitude of the accumulated time signal a difference signal, a second summation circuit subtracting the magnitude of said difference signal form the magnitude of said computed average car work time signal and producing continuously a corrected computed car work time signal the magnitude of which is proportional to said corrected computed car work time on said predetermined time scale, an electronic timer including an integrating operational amplifier measuring continuously the time elapsed from the most recent of each separate ldispatch of a car in said given direction and producing for each measurement a separate signal the magnitude of which is proportional to the measured elapsed time on said predetermined time scale; and a dispatching mechanism comparing said elapsed time signal and said corrected cornputed car work time signal and producing a signal for the dispatch of the car selected as next to be dispatched in said given direction when the compared time signals attain a predetermined relationship.

17. Apparatus for providing dispatching intervals to be used in a dispatching and control system for a plurality of in-service elevator cars being dispatched from a dispatching terminal for travel toward another terminal, comprising: computing apparatus including a circuit of interconnected operational amplifiers operating in response to conditions indicative of the existing service demand and calculating the time it would take a car to complete a round trip from one terminal to the other and back while making an estimated number of stops said service demand indicates the car will make during such travel, said apparatus continuously generating a first signal the magniture of which is on a predetermined time scale proportional to an amount of separation time by which each car could be separated from its next previously dispatched car if all successively dispatched cars were separated one from the other by equal amounts of the total calculated round trip time; an integrating operational amplifier operating as a resettable timer and generating a second signal the magnitude of which is according to said time scale proportional to the time elapsed from the most recent of each separate dispatch of a car from said dispatching terminal; an additional circuit of interconnected operational amplifiers generating a third signal the magnitude of which is proportional to the deviation from said separation time in the dispatching intervals of previously dispatched cars; and a summation circuit combining said' first, said second and said third signals by algebraically summing their magnitudes and providing dispatching intervals upon a predetermined state of combination existing; said additional circuit of interconnected operational amplifiers altering successive dispatching intervals in accordance with the deviation from said separation time in the dispatching intervals of previously dispatched cars until said dispatching intervals are substantially separating cars by said separation time.

18. Apparatus for computing a dispatching interval to be used by a dispatching and control system for a plurality of in service elevator cars which are responsive to up and down hall calls as well as to car calls in up and down cars and which are dispatched from a lower dispatching terminal for travel toward an upper terminal, comprising: an up stop time calculating apparatus operating in response to the number of up hall calls and the number of car calls in up cars and continuously generating a first signal which according to a given time scale is proportional to the amount of time which will elapse in making a number of up stops that said apparatus calculates a car traveling up between the terminals would make to serve the number of up hall calls in registration and the number of car calls in registration in up cars; a down stop time calculating apparatus operating in response to the number of down hall calls and the number of car calls in down cars and continuously generating a second signal which according to said given time scale is proportional to the amount of time which will elapse in making a number of down stops that said apparatus calculates a car traveling down between the terminals would make to serve the number of down hall calls in registration and the number of car calls in down cars; means generating a signal which on said time scale is proportional to the amount of time which elapses while a car makes a round trip without a stop; means generating a signal which on said time scale is proportional to the amount of time alotted a car for delay at the terminal landings; computing apparatus algebraically summing said first and said second signals with said round trip time signal and said terminal delay time signal and continuously providing as a sum a signal which on said time scale is proportional to the calculated time it would take one car operating alone to complete a round trip from one `terminal to the other and back while making said calculated number of stops, said computing apparatus dividing the sum it computes by the number of cars in service and pro-ducing continuously a separation time signal which on said time scale is proportional to the amount of time by which each in service car could be `separated from its next previously dispatched car if all successively dispatched cars were separated one from the other by equal amounts of the total calculated round trip time; a plurality of interconnected computing circuits including a first summation circuit and a first integrating circuit generating a first adjusting signal and a second summation circuit and a second integrating circuit generating a second adjusting signal; and a third summation circuit algebraically summing said separation time signal with said first adjusting signal and said second adjusting signal to provide a signal which on said time scale is proportional to the amount of time to be included in a dispatching interval; said first adjusting signal during each dispatching interval being proportion-al to the difference in time during that dispatching interval between, one, the amount of time which will elapse while a car travels from the lower dispatching terminal to the upper terminal as calculated by said first summation circuit by adding one-half the round trip time signal to the calculated up stop time signal and, two, the accumulated amount of time as calculated by said first integrated circuit which is actually spent by cars operating as up cars during that dispatching interval; said second adjusting signal during each dispatching interval being proportional to either the amount of time during that dispatching interval by which the second summation circuit and second integrating circuit calculates that the difference between the time represented by said second signal and the time represented by said first signal is greater than the difference between the amount of time spent by cars at said upper terminal and that spent by cars at said lower dispatching terminal, or the amount of time during that dispatching interval by which the second summation circuit and second integrating circuit calculates that the difference between the amount of time spent by cars at said lower dispatching terminal and that spent by cars at said upper terminal is greater than the difference between the time represented by said rst signal and the time represented by said second signal, or the amount of time during that dispatching interval by which the second summation circuit calculates that the time represented by second signal exceeds that represented by said first signal and/ or the second integrating circuit calculates that the time spent by cars at the lower dispatching terminal exceeds that spent by cars at the upper terminal.

19. A dispatching and control system for a plurality of elevators serving a plurality of landings including a terminal landing from which cars are dispatched at calculated timed intervals, said cars and landings having means for registering calls for service to the various landings and said system having means for selecting the car next to Ibe dispatched from said terminal landing, said system including computing apparatus comprising a plurality of interconnected operational amplifiers operating in response to calls in registration and arranged to take into consideration the number of such calls which are coincident calls, said apparatus computing the probable amount of time that will elapse between successive dispatches of the same car from said terminal and continuously generating a signal proportional to said probable `amount of time, said amount of time being based on said car traveling round trip answering a number of calls calculated by said apparatus on the basis of the calls in registration, said computing apparatus apportioning said probable amount of time signal between the two directions of travel and' also comprising an operational amplifier operating as an averaging device and dividing said probable amount of time by the number of cars operating under the control of the system to derive the least amount of time by which each said operating car could be separated from its next previously dispatched car according to said computed probable amount of time in order to have each said operating car equally spaced in time from its next previously dispatched car, said averaging device generating a signal proportional to said derived separation time; computing circuitry including an integrating operational amplifier responsive to the operating time of each car operating in a given direction during the calculation of an interval, said computing circuitry also being responsive to the apportioned probable amount of time signal for that direction and generating a signal proportional to the deviation between said derived separation time and the average time separation between cars operating in such direction during the interval; ya summation circuit operative when said derived sepration time exceeds said average time separation for decreasing said signal proportional to said derived separation time by an amount proportionate to said signal proportional to said deviation between said derived separation time and said average time separation; an electronic timer including an integrating operational amplifier operative during the calculation of each interval and generating a signal proportional to the time elapsed from the dispatch from said terminal of the next previously dispatched car; and a dispatching mechanism combining said decreased signal and said elapsed time signal and dispatching the selected car Whenever said combined signals attain a predetermined relationship.

References Cited UNITED STATES PATENTS 3,353,631 11/1967 Burgy 187-29 2,761,528 9/1956 Glaser et al. 187-29 2,889,010 6/1959 Borden et al. 187-29 3,065,824 11/ 1962 Burgy et al 187-29 3,073,417 l/1963 Lusti 187--29 ORIS L. RADER, Primary Examiner.

THOMAS E. LYNCH, Assistant Examiner.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,422 ,928 January 2l 1969 William Henry Bruns It is certified that error appears in the above identified patent and that said Letters Patent are hereby corrected as shown below:

Column 18, line 23, beginning with "time signal" Cancel all to and including "relationship" in line 26 same column 18 and insert time signal and the magnitude of said elapsed tim signal produced by said timer and generating a dispatching signal whenever said magnitudes assume a predetermined relationship Signed and sealed this 23rd day of March l97l.

(SEAL) Attest:

EDWARD M.FLETCHER,JR. WILLIAM E SCHUYLER, J Attesting Officer Commissioner of Patent 

